This project is intended to result in a fluoride glass fiber probe for endoscopic delivery of 2.9 micron Er:Yag laser energy. This corresponds to the wavelength of maximum tissue absorption for char-free, precise ablation of tissue. Potential surgical applications include coronary angioplasty, opthalmic surgery, neurosurgery, ob/gyn, and other microsurgical procedures. During Phase I, the feasibility of Er:Yag power delivery through zirconium fluoride fibers was demonstrated. It was also shown that a reliable processing technique for fabricating high optical quality fluoride glass fibers was established. Substantial improvements were made to the power handling and strength of the fibers. The Phase II research will concentrate on implementing the present process into up-scaling the production of the fluoride fibers used in various aspects of the prove development, eliminating laser damage, especially at the fiber ends, and optimizing the fiber strength by developing new and improved surface treatment techniques. The probes design will allow effective ablation in a west field without fiber damage or breakage. In addition, a rapid scan fiber spectrometer and temperature sensor will be constructed using the acouto-optic tunable filter for medical diagnostic applications.